In recent years, as the demands of digital devices with high performance and low power consumption increase, a multi-core configuration in which a plurality of processors are mounted in an embedded large scale integration (LSI) is attracting attention as a promising solution. This multi-core configuration is becoming a mainstream in a real-time system which is aimed at system control or the like.
Meanwhile, in a real-time system in which multiple cores are mounted, it is necessary to guarantee that applications executed in parallel can be scheduled without any deadline miss. As an example of a technique of solving this problem, “real-time scheduling possibility determining method and real-time system” is disclosed in Patent Literature 1.
The technique disclosed in Patent Literature 1 provides a scheduling possibility determining method usable when a plurality of processors are simultaneously necessary to execute a single task in a real-time system in which multiple cores are mounted.
Next, the technique disclosed in Patent Literature 1 will be described with reference to FIG. 13. FIG. 13 is a diagram corresponding to FIG. 2 of Patent Literature 1. A scheduling possibility determining unit 300 illustrated in FIG. 13 determines whether or not scheduling is possible by the following determination method.
Specifically, let us define:
Lk: a value that allows an actual average load of a certain time period to be necessarily equal to or more than itself when a task k incurs a deadline miss;
Uk,i: a value that is guaranteed to be equal to or larger than an average single load time of a task i during an average load time period of the task k when the task k incurs a deadline miss; and
Mi: the number of processors simultaneously used by the task i.
In this case, it is determined that real-time scheduling is possible when all of tasks satisfy:Σi=1 . . . N Mi*Uk,i≦Lk 
Using this method, in the technique disclosed in Patent Literature 1, it is possible to determine a scheduling possibility when a plurality of processors are simultaneously necessary to execute a single task.